1. Technical Field
The present disclosure relates generally to an electronic device and an antenna for an electronic device, and more particularly to an antenna suitable for a portable electronic device such as a hand held electronic device.
2. Description of the Related Art
With recent technical advances, commercialized portable electronic devices (also referred to generally as mobile communication devices) may include a wireless communication function operating in several frequency bands. Consumers who use a portable electronic device demand a smaller device having various functions. To satisfy consumer demand, manufacturers continually strive to reduce the size of components used in the portable electronic device and to integrate several functions using one component.
The effort to reduce the space requirements for components is equally made for the portable device antenna used to transmit and receive radio waves. For example, there is ongoing work to develop an antenna that fits within a small space of an electronic device while smoothly operating in various frequency bands.
In general, a portable electronic device may include at least one built-in antenna. Since the built-in antenna does not protrude to an outside of the electronic device, an external appearance is enhanced. Disadvantageously, however, a performance-to-size relation cannot be designed in a complementary manner. In particular, when a metal construction and a metal component are located near the antenna, there is a problem in that the antenna's radiation efficiency is decreased and a requisite performance over a desired band or bands is also diminished.
A conventional portable electronic device typically has sufficient space for housing an antenna and a sufficient separation distance to a metal portion of the device. An exterior of the portable electronic device is formed with a dielectric material such as plastic in general. Thus for larger devices, the antenna design did not pose significant problems. However, with the trend towards smaller and thinner devices, a space for placing the antenna has been more and more constrained, and a distance to a surrounding metal construction and metal component is becoming increasingly closer.
The aforementioned metal structure significantly contributes to not only improving mechanical robustness but also enhancing an external appearance and slimming down the device in size. Therefore, efforts are ongoing to apply this structure to a part of the electronic device, in particular, to a frame of the device.
However, it is difficult for the aforementioned conventional general built-in antenna to satisfy a requirement of a compact size, efficiency increase, and a wide band in such extreme surrounding conditions. In an attempt to solve this problem, conventional methods have: i) arranged a patterned conductor comprising the antenna radiator at a location spaced apart from a metal construction by a maximum distance possible in a narrow space allocated for the antenna; ii) processed a metal construction proximate to where the antenna is located with insert molding, or iii) increase a thickness of region of the electronic device where the antenna is located. However, in the first approach, there is a limit to how close the radiator can be to the metal construction and also effectively operate, which limits the ability to shrink the electronic device size and/or thickness. In addition, a method of performing an insert molding process on an antenna part impairs an external appearance of the antenna since there is a disparity between metal and insert molding processes in a design aspect even if it is easy to ensure radiation efficiency.
When the aforementioned metal construction is placed in a front surface of the portable device, it has been used by being connected to a main ground. However this arrangement typically results in a radiation deterioration phenomenon. That is, if there is a metal structure extended from the ground near the antenna, near field radio frequency (RF) energy induces current in a corresponding metal member and generates thermal loss and radiation loss together with lossy volume, thereby resulting in overall radiation efficiency deterioration.
To solve such problems, a method has been used in which a metal portion of an antenna is processed with insert molding and the remaining portions of a front surface of the antenna are subjected to metal processing. However, this method has a problem in that a disparity occurs between metal and insert molding processes in a design aspect.